Electrochemical fabrication of a novel ZnO/cysteic acid nanocomposite modified electrode and its application to simultaneous determination of sunset yellow and tartrazine

Trends in pulse voltammetric techniques applied to foodstuffs analysis: The food additives detection

Food additives are chemical compounds intentionally added during foodstuff production to control technological functions, such as pH, viscosity, stability (color, flavor, taste, and odor), homogeneity, and loss of nutritional value. These compounds are fundamental in inhibition the degradation process and prolonging the shelf life of foodstuffs. However, their inadequate employment or overconsumption can adversely affect consumers' health with the development of allergies, hematological, autoimmune, and reproductive disorders, as well as the development of some types of cancer. Thus, the development and application of simple, fast, low-cost, sensitivity, and selectivity analytical methods for identifying and quantifying food additives from various chemical classes and in different foodstuffs are fundamental to quality control and ensuring food safety. This review presents trends in the detection of food additives in foodstuffs using differential pulse voltammetry and square wave voltammetry, the main pulse voltammetric techniques, indicating the advantages, drawbacks, and applicability in food analysis. Are discussed the importance of adequate choices of working electrode materials in the improvements of analytical results, allowing reliable, accurate, and inexpensive voltammetric methods for detecting these compounds in foodstuffs samples.

High Luminescent Carbon Dots Derived from Fermented Beverages for Sensitive Sensing of Tartrazine in Foods

Highly luminescent carbon dots (CDs) derived from fermented beverages-kvass (K-CDs) were synthesized through a one-step hydrothermal method with ethylenediamine (EDA) as a surface passivation reagent. Purified K-CDs with a fluorescent quantum yield of 35.1% were obtained after a dialysis process. The K-CDs were characterized by TEM, FT-IR, XPS, fluorescence and UV-vis spectroscopy. The results indicated that K-CDs possess typical excitation wavelength-dependent blue fluorescence emission, and the strongest excitation and emission wavelengths are 350 nm and 440 nm, respectively. The great spectral overlap between the emission peak (440 nm) of K-CDs and the absorption peak (430 nm) of tartrazine (TAR) leads to an effective fluorescence quenching phenomenon by TAR through inner filter effect (IFE) and the calculated (lg(I0/I)) showed a linear response to TAR concentration in the range of 0.1-70 µM. The detection limit of the developed method is 23 nM for TAR, and the relative standard deviation (RSD) is 3.9% (c = 10 µM, n = 7). The fluorescent sensor for TAR based on K-CDs through the IFE mechanism possesses the characteristics of rapid, sensitive, and high selectivity. It has been successfully applied to detect of trace TAR in foods.

Recent advances in electrochemical detection of common azo dyes

PURPOSE

Food forensics is an emerging field and the initial part of this review showcases the toxic effects and the instrumental methods applied for the detection of the most commonly used azo dyes. Electrochemical detection has a lot of advantages and hence the significance of the most important techniques used in the electrochemical detection is discussed. The major part of this review highlights the surface modified electrodes, utilized for the detection of the most important azo dyes to achieve low detection limit (LOD).

METHODS

A thorough literature study was conducted using scopus, science direct and other scientific databases using specific keywords such as toxic azo dyes, electrochemical detection, modified electrodes, LOD etc. The recent references in this field have been included.

RESULTS

From the published literature, it is observed that with the growing interests in the field of electrochemical techniques, a lot of importance have been given in the area of modifying the working electrodes. The results unambiguously show that the modified electrodes outperform bare electrodes and offer a lower LOD value.

CONCLUSION

According to the literature reports it can be concluded that, compared to other detection methods, electrochemical techniques are much dependable and reproducible. The fabrication of the electrode material with the appropriate modifications is the main factor that influences the sensitivity. Electrochemical sensors can be designed to be more sensitive, more reliable, and less expensive. These sensors can be effectively used by toxicologists to detect trace amounts of harmful dyes in food samples.

A comprehensive exploration of tartrazine detection in food products: Leveraging fluorescence nanomaterials and electrochemical sensors: Recent progress and future trends

Azo dyes are widely used as food coloring agents because of their affordability and stability. Examples include brilliant blue, carmoisine, sunset yellow, allura red, and tartrazine (Tar), etc. Notably, Tar is often utilized in hazardous food goods. They are frequently flavoured and combined with food items, raising the likelihood and danger of exposure. Therefore, detecting Tar in food is crucial to prevent health risks. Fluorescence nanomaterials and electrochemical sensors, known for their high sensitivity, affordability, simplicity, and speed, have been widely adopted by researchers for Tar detection. This comprehensive paper delves into the detection of Tar in food products. It extensively covers the utilization of advanced carbon-based nanomaterials, including CDs, doped CDs, and functionalized CDs, for sensitive Tar detection. Additionally, the paper explores the application of electrochemical sensors. The paper concludes by addressing current challenges and prospects, emphasizing efforts to enhance sensitivity, and selectivity for improved food safety.

Voltammetric Sensor Based on the Combination of Tin and Cerium Dioxide Nanoparticles with Surfactants for Quantification of Sunset Yellow FCF

Sunset Yellow FCF (SY FCF) is one of the widely used synthetic azo dyes in the food industry whose content has to be controlled for safety reasons. Electrochemical sensors are a promising tool for this type of task. A voltammetric sensor based on a combination of tin and cerium dioxide nanoparticles (SnO2-CeO2 NPs) with surfactants has been developed for SY FCF determination. The synergetic effect of both types of NPs has been confirmed. Surfactants of various natures (sodium lauryl sulfate (SLS), Brij® 35, and hexadecylpyridinium bromide (HDPB)) have been tested as dispersive media. The best effects, i.e., the highest oxidation currents of SY FCF, have been observed in the case of HDPB. The sensor demonstrates a 4.5-fold-higher electroactive surface area and a 38-fold-higher electron transfer rate compared to the bare glassy carbon electrode (GCE). The electrooxidation of SY FCF is an irreversible, two-electron, diffusion-driven process involving proton transfer. In differential pulse mode in Britton-Robinson buffer (BRB) pH 2.0, the sensor gives a linear response to SY FCF from 0.010 to 1.0 μM and from 1.0 to 100 μM with an 8.0 nM detection limit. The absence of an interferent effect from other typical food components and colorants has been shown. The sensor has been tested on soft drinks and validated with the standard chromatographic method.

Applicability of a graphene oxide nanocomposite for fabrication of an electrochemical sensor for simultaneous detection of sunset yellow and rhodamine B in food samples

Developing a sensitive portable sensor for the determination of food additives is very important. Herein, a simple and sensitive electrochemical sensor has been constructed based on a carbon paste electrode (CPE) modified with graphene oxide (GO) nanosheets for the simultaneous determination of sunset yellow (SY) and rhodamine B (RhB) in phosphate buffer solution (pH = 4). The cyclic and differential pulse voltammetry (CV and DPV) results revealed two well-resolved anodic peaks for SY and RhB with a remarkable increase in oxidation signals of these colorants. Based on this, an electrochemical method was developed for the first time for the simultaneous detection of SY and RhB. Applicability of the sensor was confirmed in various concentrations of two analytes in two linear ranges of 1-20 μM for SY and 1-30 μM for RhB with a limit of detection (LOD) of 10.0 nM and 20.0 nM, respectively. Furthermore, the proposed sensor was successfully employed for the simultaneous detection of SY and RhB in food samples with recoveries of 93.1-106.0% indicating promising potential in practical application.

A modified electrode based on a 3D reduced graphene oxide and MoS2 composite for simultaneous detection of sunset yellow and tartrazine

A 3D reduced graphene oxide (3DrGO) composite loaded with cauliflower-like MoS2 was prepared. Benefiting from the synergistic effects of 3DrGO and cauliflower-like MoS2, a glassy carbon electrode (GCE) modified with the 3DrGO-MoS2 composite (3DrGO-MoS2/GCE) displays high sensing performance for sunset yellow (SY) and tartrazine (TZ) at working potentials of 0.795 and 1.034 V. Furthermore, a well separated oxidation peak potential can achieve simultaneous detection of the two analytes. Under selected conditions, the peak current exhibits a piecewise linear relationship with the SY concentration in the range of 0.05-10 μmol L-1 and 10-60 μmol L-1, and the plot of peak current versus the TZ concentration also exhibits two linear segments in the range of 0.1-6.0 μmol L-1 and 6.0-60 μmol L-1. The detection limits of SY and TZ are as low as 17.6 and 37.4 nmol L-1, respectively. The prepared 3DrGO-MoS2/GCE was applied for the determination of SY and TZ in food samples with excellent recoveries of 95.1-105.4%.

A new ratiometric molecularly imprinted electrochemical sensor for the detection of Sunset Yellow based on gold nanoparticles

Since a high dosage or excessive intake of Sunset Yellow (SY) may pose a threat to human health, it is in great demand to construct an effective method to detect and control SY. Based on the molecularly imprinted polymers (MIPs) and dual-signal output mode, a ratiometric molecularly imprinted electrochemical sensor (RMIECs) was developed for sensitive detection of SY. AuNPs not only provided a large specific surface area to enhance the electron transfer rate but also served as a reference signal (S1), together with SY signal (S2), to produce dual signals. For a proof-of-application study, RMIECs was applied to detect SY with a wide linear range from 10 nM to 100 μM and a low detection limit (LOD) of 1.60 nM (S/N = 3, n = 3). Besides, the method was applied in spiked food samples with recoveries of 94.0 ∼ 97.0 % as well as relative errors of 5.4 ∼ 8.3 %, revealing its promising potential in detection of SY.

A novel photonic chemosensor for rapidly detecting synthetic dyes in orange juice using colorimetric and spectrophotometric methods

Synthetic dyes must be monitored and regulated. We aimed to develop a novel photonic chemosensor for rapidly monitoring synthetic dyes based on colorimetric (chemical interactions with optical probes using microfluidic paper-based analytical devices) and UV-Vis spectrophotometric methods. Various types of gold and silver nanoparticles were surveyed to identify the targets. In the presence of silver nanoprisms, the naked eye could visualize the unique and distinctive color changes of Tartrazine (Tar) to green and Sunset Yellow (Sun) to brown; UV-Vis spectrophotometry validated the results. The developed chemosensor showed linear ranges of 0.07-0.3 mM and 0.05-0.2 mM for Tar and Sun, respectively. Sources of interference had minimal effects, confirming the appropriate selectivity of the developed chemosensor. Our novel chemosensor demonstrated excellent analytical performance for measuring Tar and Sun in several types of orange juice as real samples, confirming its incredible potential for use in the food industry.

Designing nano ranged electrode modifier comprised of samarium niobate anchored carbon nanofibers for trace level detection of food colourant: Tartrazine

Tartrazine (TRZ) is a predominantly used food color in food processing industries which is soluble in water to produce a orange colour. This food colorant is categorized under the mono-azo pyrazolone dye group known for the perilous azo group (-NN-) attached to the aromatic ring that threatens human health. In consideration of these aspects, a novel TRZ sensing platform with advanced electrode material is designed by incorporating nanotechnology with chemical engineering. This innovative sensor is prepared by electrode modification through a nano ranged electrode modifier of SmNbO₄ decorated on the enmeshed carbon nanofibers. This is the first report on the investigation of SmNbO₄/f-CNF as an electrode modifier to extricate the superlative electrochemical properties towards TRZ detection and protracted its practicality to food samples with a lower limit of detection (2 nmolL^-1), broad linear range, good selectivity, and functional stability.

Analytical Applicability of Graphene-Modified Electrode in Sunset Yellow Electrochemical Assay

Due to the recent increase in average living standards, food safety has caught public attention. It is necessary to conduct a qualitative and quantitative rapid test of prohibited food additives since the inclusion of food additives or the improper usage of synthetic dyes can negatively impact on the human health. Herein, a highly sensitive method for Sunset Yellow detection based on a glassy carbon electrode modified with few-layer graphenes was proposed. The electrochemical behavior of SY at the GR-exf/GCE modified surface was investigated by Cyclic Voltammetry, Square Wave Voltammetry, Electrochemical Impedance Spectroscopy and Amperometry. The influences of pH, scan rate, and interfering species were studied. Under optimized conditions, the developed sensor shows good linearity over a broad SY concentration range, e.g., 0.028-30 µM, with a low limit of detection (LOD = 0.0085 µM) and quantification (LOQ = 0.028 µM) (data obtained by amperometric technique). Furthermore, the modified electrode shows good selectivity, precision and sensitivity and has been successfully applied for SY quantification from commercially available pharmaceutical formulation as well as from candy bars and orange juice.

Electropolymerized 4-Aminobenzoic Acid Based Voltammetric Sensor for the Simultaneous Determination of Food Azo Dyes

Electrochemical sensors with polymeric films as a sensitive layer are of high interest in current electroanalysis. A voltammetric sensor based on multi-walled carbon nanotubes (MWCNTs) and electropolymerized 4-aminobenzoic acid (4-ABA) has been developed for the simultaneous determination of synthetic food azo dyes (sunset yellow FCF and tartrazine). Based on the voltammetric response of the dyes' mixture, the optimal conditions of electropolymerization have been found to be 30-fold potential scanning between -0.3 and 1.5 V, at 100 mV s^-1 in the 100 µmol L^-1 monomer solution in phosphate buffer pH 7.0. The poly (4-ABA)-based electrode shows a 10.5-fold increase in its effective surface area and a 17.2-fold lower electron transfer resistance compared to the glassy carbon electrode (GCE). The sensor gives a sensitive and selective response to sunset yellow FCF and tartrazine, with the peak potential separation of 232 mV in phosphate buffer pH 4.8. The electrooxidation parameters of dyes have been calculated. Simultaneous quantification is possible in the dynamic ranges of 0.010-0.75 and 0.75-5.0 µmol L^-1 for both dyes, with detection limits of 2.3 and 3.0 nmol L^-1 for sunset yellow FCF and tartrazine, respectively. The sensor has been tested on orange-flavored drinks and validated with chromatography.

Highly Sensitive Electrochemical Sensor for Sunset Yellow Based on Electrochemically Activated Glassy Carbon Electrode

Electrochemically activated glassy carbon electrode (AGCE) was fabricated and applied for sensitive and selective detection of sunset yellow (SY). The electroanalysis of SY was investigated by square wave voltammetry (SWV). Owed to the specific oxygen-contained functional groups and the outstanding conductivity of AGCE, the proposed sensor exhibits an enhanced oxidation peak current of SY when compared with non-activated glass carbon electrode (GCE). Under the optimal analytical conditions, the oxidation peak current is linear with SY concentration in the range of 0.005–1.0 μM. The low limit of detection is 0.00167 μM (S/N = 3). This method is applied for the detection of SY in the actual samples. The recovery is between 96.19 and 103.47%, indicating that AGCE is suitable for the determination of SY in beverage sample.

An Electrochemical Sensor Based on Carbon Paper Modified with Graphite Powder for Sensitive Determination of Sunset Yellow and Tartrazine in Drinks

The paper describes the development of an electrochemical sensor to be used for the determination of synthetic food colorants such as Sunset Yellow FCF (SY) and Tartrazine (TZ). The sensor is a carbon paper (CP) electrode, manufactured by using hot lamination technology and volume modified with fine-grained graphite powder (GrP). The sensor (GrP/CP) was characterized by scanning electron microscopy, energy dispersive spectrometry, electrochemical impedance analysis, cyclic, linear sweep and differential pulse voltammetry. The mechanism of SY and TZ electrochemical oxidation on GrP/CP was studied. The developed sensor has good electron transfer characteristics and low electron resistance, high sensitivity and selectivity. Applying the differential pulse mode, linear dynamic ranges of 0.005–1.0 μM and 0.02–7.5 μM with limits of detection of 0.78 nM and 8.2 nM for SY and TZ, respectively, were obtained. The sensor was used to detect SY and TZ in non-alcoholic and alcoholic drinks. The results obtained from drink analysis prove good reproducibility (RSD ≤ 0.072) and accuracy (recovery 96–104%).

Application electrochemical sensor based on nanosheets G-C3N4/CPE by square-wave anodic stripping voltammetric for measure amounts of toxic tartrazine color residual in different drink and foodstuffs

The present work describes a method (SWASV) techniques for measure of tartrazine color a harmful compound present in real samples, and the extremely harmful to humans and animals even at low concentrations using G-C₃N₄ nanosheets sensor. Here, we report the use of an electrochemical approach for analytical determination of toxic tartrazine that takes 150 s. The calibration curve was linear in range of the (0.02-18.0 µmol L^-1). The current response was linearly proportional to the tartrazine concentration with a R²∼ 0.999. We demonstrated a sensitivity a limit of detection of (0.022 µmol L^-1). Finally, sensor nanosheets G-C₃N₄/CPE introduced to measure toxic tartrazine in different drink and foodstuff samples was used and the chemical nanosheets G-C₃N₄/CPE sensor made it possible as an excellent sensor with reproducibility for determination other samples.

One-Step Fabrication of Nickel-Electrochemically Reduced Graphene Oxide Nanocomposites Modified Electrodes and Application to the Detection of Sunset Yellow in Drinks

This work describes a straightforward method using one-step preparation of graphene/nickel nanocomposite materials from low-cost materials including graphene oxide and nickel metal. Repetitive CVs lead to the simultaneous deposition of metallic nickel nanoparticles and reduced graphene oxide sheets onto glassy carbon electrode. The obtained nanocomposite-modified surfaces were characterised by cyclic voltammetry, differential pulse voltammetry and field emission scanning electron microscopy. The result demonstrated the ability to produce nickel nanoparticles with a small size of about 20 nm, uniformly dispersed on a graphene oxide matrix. The ERGO-NiNP nanocomposite could be used as a sensor material exhibiting high performance; it is used here in order to detect Sunset Yellow (SY) and for quantification in complex media. The sensor enables rapid quantification of SY with a good linearity (R2 = 0.996) in the range of 10–1000 nM, together with a low detection limit of 3.7 nM (equivalent to 1.7 µg L−1) and a high sensitivity up to 7 µA/µM. The sensor also displays high reliability with a RSD value = 1.08 (n = 10) and good reusability (signal response variation below 5% after 5 detection/cleaning cycles). Finally, we demonstrate how this GCE/ERGO-NiNP sensor can be used for the successful determination of SY in commercial soft drink samples with an acceptable deviation below 6.4% when compared to HPLC method.

Fe3O4@PDA@PANI core-shell nanocomposites as a new adsorbent for simultaneous preconcentration of Tartrazine and Sunset Yellow by ultrasonic-assisted dispersive micro solid-phase extraction

In this research, novel magnetic Fe₃O₄@PDA@PANI core-shell nanoparticles were designed and fabricated as an efficient adsorbent in the service of ultrasound-assisted dispersive micro-solid phase extraction for simultaneous preconcentration of Sunset Yellow (SY) and Tartrazine (Tar) before UV-Vis spectrophotometric detection. This adsorbent was fully characterized by Fourier Transform Infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Energy Dispersive X-ray (EDX) analysis. To overcome the spectral overlapping of SY and Tar dyes, the derivative spectrophotometric method was successfully used for the simultaneous detection of dyes in their binary solutions. The operating parameters affecting preconcentration efficiency and spectrophotometric determination were optimized. Under optimal conditions, the limit of detections (LOD) was obtained 0.2 and 0.5 ng mL^-1 for SY and Tar, respectively. The adsorption capacity and reusability of core-shell nanoparticles were significant. The satisfactory results of analysis of a few real samples indicate that the method is very favored in the analysis of various complex matrices.

Latest advances on the nanomaterials-based electrochemical analysis of azo toxic dyes Sunset Yellow and Tartrazine in food samples

Azo-dyes such as Allura Red, Carmoisine, Amaranth, Sunset Yellow (SY), Brilliant Blue, Tartrazine (Tz), etc., are popular as food coloring agents due to their low cost and stability. SY and Tz are the most used members of this group of dyes since they have similar colors and are usually used together in food products. Despite their advantageous industrial use, they exhibit a risk toxicity profile with adverse effects such as allergy, asthma, carcinogenicity, genotoxicity, cytotoxicity, anxiety, etc. Therefore, the United States Food and Drug Administration (FDA) and European Food Safety Authority (EFSA) regulate the permissions for using these compounds to provide safe food products for consumers and prevent adverse effects both short and long-term. Considering all of these, for the analysis of azo toxic dyes, highly sensitive, low-cost, simple, and rapid sensors are necessary. Electrochemical nanosensors, which combine the unique features of electrochemistry and nanotechnology, are devices with all these advantages and are widely used for the determination of azo dyes. SY and Tz step forth as the most used food dyes in the class of azo-toxic dyes. They are often preferred together in food products, increasing the occurrence and exposure risk. Therefore, the analysis of Sunset Yellow and Tartrazine in food products has significant importance. In this review, the latest nanomaterial-based approaches for the electrochemical sensors on the analysis of SY and Tz in food samples were evaluated in terms of used nanomaterials and applied food samples.

An electrochemical sensor based on hierarchical nickel oxide nanostructures doped with indium ions for voltammetric simultaneous determination of sunset yellow and tartrazine colorants in soft drink powders

The current study was designed to develop a single-step and simple approach to effectively fabricate three-dimensional raspberry-like In³⁺/NiO hierarchical nanostructures (In³⁺/NiO RLHNSs) as a modifier, which was subsequently characterized by the techniques of X-ray diffraction (XRD), energy dispersive spectrometry (EDS) and field emission scanning electron microscopy (FE-SEM). The new prepared nano-modifier was practically used to co-detect electrochemically sunset yellow and tartrazine dyes. Potent sensitivity and acceptable selectivity were obtained for the produced In³⁺/NiO RLHNSs to co-detect both the food colorants, thus providing oxidation peaks in differential pulse voltammetry (DPV) with a peak potential separation of ca. 190 mV. The results showed a 5.14-fold and 8.07-fold increase in the electrochemical response of our modified electrode to sunset yellow and tartrazine, respectively, compared to the control (the unmodified electrode). Limits of detection of 2.7 and 3.1 nM were calculated for sunset yellow and tartrazine, respectively. The results from the interaction of common food additives showed satisfactory outcomes for the application of this method in determining sunset yellow and tartrazine in several beverage specimens. Other useful documentation was obtained for the production of portable food additive sensors.

Improved solid phase extraction for selective and efficient quantification of sunset yellow in different food samples using a novel molecularly imprinted polymer reinforced by Fe3O4@UiO-66-NH2

The overuse of synthetic dyes in food products has gradually increased in recent years, resulting food safety and human health has become a global issue. An innovative design of a magnetic molecularly imprinted polymer (Fe3O4@UiO-66-NH2@MIP) for efficient, fast, and selective determination of sunset yellow (SY) from different food products was described in this study. The absorption properties of Fe3O4@UiO-66-NH2@MIP were elucidated by adsorption kinetics, isotherms, reusability, and selectivity experiments. Because of the incorporation of porous Fe3O4@UiO-66-NH2nanocomposite into molecularly imprinted polymer an efficient nanosorbent with a short equilibrium time, a high adsorption capacity, and a good imprinting factor was finally obtained. The porous Fe3O4@UiO-66-NH2@MIP are also used for quantification of the SY. Under optimal conditions, good linearity (R2 0.9964) in the range of 1.0-120 mg L-1 and a low limit of detection (0.41 mg L-1) was observed with satisfactory recoveries (92.50-106.1%) and excellent reusability (RSD ≤ 6.6% after 12 cycles).

Recent advances in ZnO nanostructure-based electrochemical sensors and biosensors

Nanostructured metal oxides, such as zinc oxide (ZnO), are considered as excellent materials for the fabrication of highly sensitive and selective electrochemical sensors and biosensors due to their good properties, including a high specific surface area, high catalytic efficiency, strong adsorption ability, high isoelectric point (IEP, 9.5), wide band gap (3.2 eV), biocompatibility and high electron communication features. Thus, ZnO nanostructures are widely used to fabricate efficient electrochemical sensors and biosensors for the detection of various analytes. In this review, we have discussed the synthesis of ZnO nanostructures and the advances in various ZnO nanostructure-based electrochemical sensors and biosensors for medical diagnosis, pharmaceutical analysis, food safety, and environmental pollution monitoring.

Development of a highly sensitive fluorescence method for tartrazine determination in food matrices based on carbon dots

In this work, an ultrasensitive sensing system based on fluorescent carbon dots (CDs) was developed for the tartrazine (Tar) determination. The CDs were prepared via a simple one-pot hydrothermal method with m-phenylenediamine as the only precursor. The physical and chemical properties were in detail characterized by transmission electron microscopy (TEM), MALDI-TOF MS, UV-vis absorption and photoluminescence (PL) spectroscopy, elemental analysis, and Fourier transform infrared spectroscopy (FTIR). Upon exposure to Tar, the fluorescence of CDs was efficiently quenched via the dynamic interaction between CDs and Tar as well as the inner filter effect (IFE). With this information, the CDs were proposed as a fluorescence probe for Tar detection. It was found that CDs had high sensitivity and selectivity for Tar sensing, and the linear relationship was observed in the range of 0.01-25.0 μM with the corresponding detection limit (3σ/k) of 12.4 nM, which is much more sensitive than any of the existed CD-based sensing platform. The investigated sensing system was finally utilized for Tar sensing in various food matrices with a high degree of accuracy. The spiked recoveries were in a range of 96.4-105.2%, and the relative standard deviations (RSDs) were lower than 4.13%. This work highlights the great application prospects of CDs for Tar sensing in a rapid, simple, and sensitive way.

Assessment of the use of boron-doped diamond electrode for highly sensitive voltammetric determination of the azo-dye carmoisine E-122 in food and environmental matrices

A new protocol for the analysis of the azo-dye carmoisine (CMS) is presented by coupling differential pulse voltammetry (DPV) with a cathodically pretreated boron-doped diamond electrode (CPT-BDDE), in phosphate buffer solution (pH 2.0). The CMS presented diffusion-controlled oxidation and reduction peaks at +0.88 and -0.15 V vs Ag/AgCl, respectively. The effect of the pretreatment conditions, pH, and supporting electrolytes were evaluated to the voltammetric determination of CMS. Under optimized conditions, the differential pulse voltammetric signals for CMS were linear over the concentration range of 0.059-1.31 μmol L^-1 and 0.010-0.079 μmol L^-1 with limits of detection of 7.0 and 3.0 nmol L^-1, for the anodic and cathodic processes respectively. The method was precise for CMS determination (RSD < 5.0%) and selective against other dyes. The developed protocol was successfully applied in the analysis of CMS in surface water and foodstuffs with accurate results in comparison with those obtained using a validated spectrophotometric method.

A simple strategy for the synthesis of flower-like textures of Au-ZnO anchored carbon nanocomposite towards the high-performance electrochemical sensing of sunset yellow

Consumption of sunset yellow (SY) above a certain concentration through food products may leads to adverse health issues. Therefore, it is imperative to develop technologies for rapid and selective detection of SY. Herein, a flower-like reduced graphene oxide (rGO)-graphitic carbon nitride (g-CN)/ZnO-Au nanoparticle (NPs) has been prepared and utilized for the specific detection of SY. The fabricated rGO-g-CN/ZnO-AuNPs composite was characterized and investigated by XRD, FTIR, SEM, TEM, XPS, EIS, and voltammetry techniques. Characterization techniques elucidated the deposition of ZnO-AuNPs on to the rGO-g-CN and successful fabrication of rGO-g-CN/ZnO-AuNPs composite. rGO-g-CN/ZnO-AuNPs composite possesses excellent catalytic activity for the oxidation of SY. Developed rGO-g-CN/ZnO-AuNPs sensor exhibits LOD of 1.34 nM for SY concentrations ranging from 5 to 85 nM. Noteworthily, the sensor has been successfully employed for the detection and recovery of SY in real-time samples. Fabricated composite opens up new avenues to develop electrochemical sensor for food safety.

Determination of color additive tartrazine (E 102) in food samples after dispersive solid phase extraction with a zirconium-based metal-organic framework (UiO-66(Zr)-(COOH)2)

A new and rapid dispersive solid phase extraction method by using a green-synthesised UiO-66(Zr)-(COOH)₂ (Zr-BTeC) adsorbent with body-centred cubic (bcu) topology was developed for determination of tartrazine in food samples. Zr-BTeC was used for the first time as an adsorbent for tartrazine. It was synthesised and characterised by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, Brunauer-Emmett-Teller surface area analysis, and zeta potential measurements. Tartrazine was determined at 405 nm spectrophotometrically. Experimental conditions were optimised in order to achieve quantitative recoveries. The sample acidity was found to be 0.02 mol L^-1 HCl. The amount of Zr-BTeC was 10 mg. Both adsorption and elution contact times were only 5 s without the need for vortexing. Elution was with 2 mL of 0.5 mol L^-1 NH₃. A sample volume of 45 mL was selected as optimum. The adsorption capacity for tartrazine with Zr-BTeC was found to be 185 mg g^-1 and the adsorbent was reusable up to 40 cycles. The tartrazine concentrations found by the developed method in food supplements were compared with the results obtained by HPLC method for the same samples. Statistical analysis results showed that there are insignificant differences between the results of the two methods (p = .05). The method was successfully applied to the determination of tartrazine in spiked chewing gums, lemon flavoured icing glaze, and jelly samples.

Synthetic Food Dyes – Some Aspects Of Use And Methods Of Determination

Color is one of the key ingredients for increasing the appetizing of food, so food dyes have become firmly established in food production technologies. However, with the acquisition of toxicity data of synthetic food dyes (SFD), there were restrictions and standards for their content in food have emerged. Numerous papers published in recent years demonstrate the importance of the problem of the use and definition of SFD. The review contains over 180 literary references in the field of usage and methods of determination of synthetic food dyes, among them regulatory documents (regulations), official internet resources of international and Ukrainian organizations, review articles and original works. Varieties of chromatography, enzyme-linked immunoassay, optical and electrochemical methods are used to identify and determine SFD. Special attention was paid to voltammetry (VA) as a method that is cheaper than chromatography and completely satisfies selectivity, sensitivity, reliability requirements and is compatible with the concept of green analytical chemistry, as it doesn't need organic solvents. Moreover, single sweep voltammetry can be considered as a screening method with low limits of determination and rapid respons